Biomechanics, Bioactive and Biomimetic Philosophy in Restorative Dentistry ̶ Quo vadis?

INTRODUCTION: In recent years, restorative dentistry has embraced various techniques, including direct, semi-direct, and indirect restorations, to address the replacement of lost tooth tissue. The focus has been on integrating the principles of Biomechanics, Bioactivity, and Biomimicry (3-Bio) as key drivers behind these innovations. METHODS: Three enthusiastic researchers in dental materials have come together to collaborate on writing a concise opinion article addressing the three aspects of restorative dental materials: Biomechanics, Bioactivity, and Biomimetic principles. Their aim is to provide readers with relevant information on the 3-Bio concept, offering insights into the innovative approaches shaping modern restorative dentistry. RESULTS: Developing restorative materials with interactive properties aligned with the 3-Bio concept poses a significant challenge. Currently, dentistry lacks a comprehensive system in this regard. Though, the development of dental materials based on the 3-Bio concept could potentially elicit positive mechanical and biological responses in targeted tooth tissues. CONCLUSION: Assessing several parameters through a battery of in vitro and in silico assays could help in tailoring the different aspects of the 3-Bio concept, spanning from bioactivity to biomimetics via biomechanics. This approach could allow the prediction and translation of the clinical performance of the assessed restorative materials. CLINICAL SIGNIFICANCE: The findings of this opinion article highlight that the development of restorative materials aligned with the 3-Bio concept could enhance the management of dental defects and extend the longevity of bonded restorations, thereby improving patient care through tissue preservation. The authors believe that more collective efforts between clinicians, researchers, and even industrial partners are required to fully understand the correlation between bioactive behaviour, biomechanical limitations, and biomimetics to provide suitable restorative materials for specific clinical applications.

Development of Chlorhexidine-loaded Lipid Nanoparticles Incorporated in a Bioceramic Endodontic Sealer.

INTRODUCTION: This study aimed to assess BioRoot RCS (BR) incorporating liposomal chlorhexidine digluconate (CHX) for its antibacterial activity, drug release capacity, and physicochemical properties. METHODS: Drug release of CHX liposomal formulations in combination with BR was evaluated spectrophotometrically and through mathematical release models for 30 days. A selected combination was evaluated for antimicrobial properties against Enterococcus faecalis biofilm growth on human dentin. Cytotoxicity was assessed following the ISO 10993-5:2019 standard on days 1, 3, and 7. Physicochemical properties were evaluated through setting time, Fourier transform infrared spectroscopy, solubility, contact angle, and film thickness. RESULTS: From BR, liposomal CHX released up to 7-fold higher CHX than CHX solution (P < .05), following a triphasic drug release pattern compared to the CHX solution, which followed a quasi-Fickian diffusion. BR combined with a selected liposomal CHX completely inhibited E. faecalis biofilm growth compared to the combination of BR with CHX solution and the control group (P < .05). Liposomal CHX decreased the contact angle (P < .05) and solubility but increased cytotoxicity (P < .05) of BR, staying above the ISO threshold. None of the other physicochemical characteristics tested differed from BR (P > .05). CONCLUSION: This liposomal formulation improved CHX release from BR, enhancing the antibacterial effectiveness. It presents a promising approach for local antibiofilm therapy in endodontics without substantially altering the physicochemical characteristics of BR.

Artificial intelligence and smile design: An e-Delphi consensus statement of ethical challenges.

PURPOSE: Smile design software increasingly relies on artificial intelligence (AI). However, using AI for smile design raises numerous technical and ethical concerns. This study aimed to evaluate these ethical issues. METHODS: An international consortium of experts specialized in AI, dentistry, and smile design was engaged to emulate and assess the ethical challenges raised by the use of AI for smile design. An e-Delphi protocol was used to seek the agreement of the ITU-WHO group on well-established ethical principles regarding the use of AI (wellness, respect for autonomy, privacy protection, solidarity, governance, equity, diversity, expertise/prudence, accountability/responsibility, sustainability, and transparency). Each principle included examples of ethical challenges that users might encounter when using AI for smile design. RESULTS: On the first round of the e-Delphi exercise, participants agreed that seven items should be considered in smile design (diversity, transparency, wellness, privacy protection, prudence, law and governance, and sustainable development), but the remaining four items (equity, accountability and responsibility, solidarity, and respect of autonomy) were rejected and had to be reformulated. After a second round, participants agreed to all items that should be considered while using AI for smile design. CONCLUSIONS: AI development and deployment for smile design should abide by the ethical principles of wellness, respect for autonomy, privacy protection, solidarity, governance, equity, diversity, expertise/prudence, accountability/responsibility, sustainability, and transparency.

Concordance of judgement: A tool to foster the development of professionalism in dentistry.

INTRODUCTION: Developing professionalism notably involves learning how to make professional judgements in ambiguous situations. The Concordance of Judgement Test (CJT) is a learning tool that was proposed to develop professionalism competencies, but it was never performed in dentistry or used with a synchronous methodology. The present study evaluated the feasibility of the use of CJT in the context of dental education, to foster professionalism and stimulate reflexivity and discussion. MATERIALS AND METHODS: After different steps of optimization, a questionnaire presenting 12 vignettes was submitted to 33 Canadian students. Second, after an additional optimization, a questionnaire of 7 vignettes was submitted to 87 French students. An immediate educational feedback was proposed after each vignette to promote reflexivity and discussions during the experience. RESULTS: The overall experience of the students was reported as good, thanks to the feedback of real-life situations. This promoted reflexivity and stimulated discussion between students and educators regarding professionalism issues. The students considered CJT as a relevant and well-adapted tool, and reported positive feelings regarding the inter-university aspect of the activity. The mean score of the panel members was close to 80/100 and the mean score of the students was 5 to 10 points lower, which is in agreement with docimological performance. CONCLUSION: The results suggested that the use of CJT in a synchronous way was a feasible and relevant tool to motivate the students to improve their professionalism, and to stimulate their reflexivity and discussion. The students reported positive experience with CJT, and we believe that this tool can be integrated in the dental curriculum.

Developing Advanced Patient-Specific In Silico Models: A New Era in Biomechanical Analysis of Tooth Autotransplantation.

INTRODUCTION: As personalized medicine advances, there is an escalating need for sophisticated tools to understand complex biomechanical phenomena in clinical research. Recognizing a significant gap, this study pioneers the development of patient-specific in silico models for tooth autotransplantation (TAT), setting a new standard for predictive accuracy and reliability in evaluating TAT outcomes. METHODS: Development of the models relied on 6 consecutive cases of young patients (mean age 11.66 years ± 0.79), all undergoing TAT procedures. The development process involved creating detailed in silico replicas of patient oral structures, focusing on transplanting upper premolars to central incisors. These models underpinned finite element analysis simulations, testing various masticatory and traumatic scenarios. RESULTS: The models highlighted critical biomechanical insights. The finite element models indicated homogeneous stress distribution in control teeth, contrasted by shape-dependent stress patterns in transplanted teeth. The surface deviation in the postoperative year for the transplanted elements showed a mean deviation of 0.33 mm (±0.28), significantly higher than their contralateral counterparts at 0.05 mm (±0.04). CONCLUSIONS: By developing advanced patient-specific in silico models, we are ushering in a transformative era in TAT research and practice. These models are not just analytical tools; they are predictive instruments capturing patient uniqueness, including anatomical, masticatory, and tissue variables, essential for understanding biomechanical responses in TAT. This foundational work paves the way for future studies, where applying these models to larger cohorts will further validate their predictive capabilities and influence on TAT success parameters.

Investigation of the early apical release from endodontic hydrogels: A 3D printed model.

AIM: Regenerative Endodontic Procedures (REPs) using new materials such as hydrogels aim to replace current endodontic treatments, but numerous limitations are to overcome. Apical release was little explored in previous studies, especially regarding hydrogels that incorporate molecules, such as growth factors and antibiotics. Apical release is a key mechanism in achieving regeneration, as it could regulate disinfection or cell colonization. Few models exist for apical release, limiting the transfer of these devices from bench to bedside. This study aims to design a simple and standardized model to identify parameters that influence the early apical release kinetic of molecules from endodontic hydrogels. METHODOLOGY: Endodontic Release Inserts (ERI) were designed to mimic the situation of an immature incisor using three different diameters (Ø 0.5 to 2 mm) and to allow the study of the early release from a hydrogel in a 96-well plate. ERI was produced with a 3D printing machine. The kinetic release was investigated using 2 fluorescent, hydrophobic (BDP-500) and hydrophilic (Fluorescein) molecules, in different hydrogels (fibrin and agarose) and in various media (PBS or serum). The release kinetics were estimated by measuring the fluorescence at different time points (1 to 24 h). RESULTS: ERI use made it possible to report that apical diameters increase from 500 to 1000 µm was associated with an increase in release from 4.02 ± 1.63% to 11.53 ± 2.38% over 24 h. It also allowed us to report that bottom solution composition change from PBS to human serum was associated with an increase in the release of fatty acid molecules, whilst a decrease in the hydrogel concentration was associated with a variation in release kinetics. Moreover, nano-encapsulation of a molecule was associated with a decreased release over the first 24 h from 5.25 to 0%. CONCLUSION: ERI use enables investigation of the parameters influencing release kinetics from endodontic hydrogels. Further investigations are necessary to evaluate the interaction of these parameters with each other, in animal models and clinic.

Bioactive Endodontic Hydrogels: From Parameters to Personalized Medicine.

Regenerative endodontic procedures (REPs) aim at recreating dental pulp tissue using biomaterials such as hydrogels. Their bioactivity is mostly related to the nature of biomolecules or chemical compounds that compose the endodontic hydrogel. However, many other parameters, such as hydrogel concentration, bioactive molecules solubility, and apex size, were reported to influence the reciprocal host-biomaterial relationship and hydrogel behavior. The lack of knowledge regarding these various parameters, which should be considered, leads to the inability to predict the clinical outcome and suggests that the biological activity of endodontic hydrogel is impossible to anticipate and could hinder the bench-to-bedside transition. We describe, in this review, that most of these parameters could be identified, described, and studied. A second part of the review lists some challenges and perspectives, including development of future mathematical models that are able to explain, and eventually predict, the bioactivity of endodontic hydrogel used in a clinical setting.

Real-time simulation of the transplanted tooth using model order reduction.

The biomechanics of transplanted teeth remain poorly understood due to a lack of models. In this context, finite element (FE) analysis has been used to evaluate the influence of occlusal morphology and root form on the biomechanical behavior of the transplanted tooth, but the construction of a FE model is extremely time-consuming. Model order reduction (MOR) techniques have been used in the medical field to reduce computing time, and the present study aimed to develop a reduced model of a transplanted tooth using the higher-order proper generalized decomposition method. The FE model of a previous study was used to learn von Mises root stress, and axial and lateral forces were used to simulate different occlusions between 75 and 175N. The error of the reduced model varied between 0.1% and 5.9% according to the subdomain, and was the highest for the highest lateral forces. The time for the FE simulation varied between 2.3 and 7.2 h. In comparison, the reduced model was built in 17s and interpolation of new results took approximately 2.10-2s. The use of MOR reduced the time for delivering the root stresses by a mean 5.9 h. The biomechanical behavior of a transplanted tooth simulated by FE models was accurately captured with a significant decrease of computing time. Future studies could include using jaw tracking devices for clinical use and the development of more realistic real-time simulations of tooth autotransplantation surgery.

Next generation antibacterial strategies for regenerative endodontic procedures: A scoping review.

BACKGROUND: The clinical results following regenerative endodontic procedures (REPs) vary according to numerous parameters, including the presence of bacteria. This limitation reduces the indications for REPs and calls for the development of next generation antibacterial strategies (NGAS) providing alternatives to current antibacterial strategies (CAS) such as double or triple antibiotic paste (DAP/TAP) and (Ca(OH)2). OBJECTIVES: The present scoping review aims to describe the current trends regarding the use of such strategies and highlight future perspectives. METHODS: Four databases (PUBMed, Cochrane, ClinicalTrials and Science Direct) were searched until 1st May 2023. RESULTS: A total of 918 records were identified, 133 were screened and assessed for eligibility, and 87 articles were included. The findings show that (1) clinical studies are only available for CAS, (2) although next generation strategies are the most studied approach since 2017, they are all at the pre-clinical stage, (3) most of the next generation strategies use galenic forms which offer cell support and colonization and which simultaneously contain antibacterial molecules as alternatives to CAS and to antibiotics in general, (4) standardization is required for future research, specifically regarding the bacterial strains studied, the use of biofilm studies and the cellular behaviour assessments. CONCLUSION: Although NGAS are promising strategies to improve REPs in the context of infection, the current evidence is mostly limited to pre-clinical studies. Further methodological improvement is required to allow relevant comparisons between studies and to reduce the time from bench to bedside.

Assessment of guide fitting using an intra-oral scanner: An in vitro study.

OBJECTIVES: The aim of this study was to evaluate the capacity of an intra-oral scanner (IOS) to assess the position of an endodontic guide in vitro. METHODS: Fourteen extracted human teeth were placed into a maxillary model and scanned using computed tomography and a reference laboratory scanner. An ideal endodontic guide was then created and modified by adding defects of different thicknesses to simulate incorrect positions: 50 µm, 150 µm, 400 µm, and 1000 µm. For each thickness, guides were printed three times and each guide was scanned by three experimented operators using a Trios 4 IOS (3Shape, Copenhagen, Denmark). The 36 scans were compared using a best-fit alignment to the master model without defect to define the accuracy of the method and the positioning error. RESULTS: The IOS presented a mean trueness of 1.28 µm (SD= 12.70) and a mean precision of 11.52 µm (SD= 62.17). Considering all sizes of defect, the mean measured position of the endodontic guide was highly correlated (R>0.99) with the expected position. Compared to the ideal guide, there was a mean linear deviation of 46.11 µm (SD= 23.21) and a mean angular deviation of 5.9° (SD= 1.2); this deviation was not influenced by the operator. CONCLUSION: The present study found that an IOS had good performance to detect a positioning error of the endodontic guide in vitro. CLINICAL SIGNIFICANCE: This new application of IOS has a promising potential in clinical practice to assist practitioners during the fitting of guides.

Stronger than Ever: Multifilament Fiberglass Posts Boost Maxillary Premolar Fracture Resistance.

This paper investigates the influence of cavity configuration and post-endodontic restoration on the fracture resistance, failure mode and stress distribution of premolars by using a method of fracture failure test and finite elements analysis (FEA) coupled to Weibull analysis (WA). One hundred premolars were divided into one control group (Gcontr) (n = 10) and three experimental groups, according to the post-endodontic restoration (n = 30), G1, restored using composite, G2, restored using single fiber post and G3, restored using multifilament fiberglass posts (m-FGP) without post-space preparation. Each experimental group was divided into three subgroups according to the type of coronal cavity configuration (n = 10): G1O, G2O, and G3O with occlusal (O) cavity configuration; G1MO, G2MO, and G3MO with mesio-occlusal (MO); and G1MOD, G2MOD, and G3MOD with mesio-occluso-distal (MOD). After thermomechanical aging, all the specimens were tested under compression load, and failure mode was determined. FEA and WA supplemented destructive tests. Data were statistically analyzed. Irrespective of residual tooth substance, G1 and G2 exhibited lower fracture resistance than Gcontr (p < 0.05), whereas G3 showed no difference compared to Gcontr (p > 0.05). Regarding the type of restoration, no difference was highlighted between G1O and G2O, G1MO and G2MO, or G1MOD and G2MOD (p > 0.05), whereas G3O, G3MO, and G3MOD exhibit higher fracture resistance (p < 0.05) than G1O and G2O, G1MO and G2MO, and G1MOD and G2MOD, respectively. Regarding cavity configuration: in G1 and G2, G1O and G2O exhibited higher fracture resistance than G1MOD and G2MOD, respectively (p < 0.05). In G3, there was no difference among G3O, G3MO and G3MOD (p > 0.05). No difference was found among the different groups and subgroups regarding the failure mode. After aging, premolars restored with multifilament fiberglass posts demonstrated fracture resistance values comparable to those of an intact tooth, irrespective of the different type of cavity configuration.

Do the Mechanical Properties of Calcium-Silicate-Based Cements Influence the Stress Distribution of Different Retrograde Cavity Preparations?

The aim of the present study was to investigate the influence of the mechanical properties of three different calcium-silicate-based cements on the stress distribution of three different retrograde cavity preparations. Biodentine™ "BD", MTA Biorep "BR", and Well-Root™ PT "WR" were used. The compression strengths of ten cylindrical samples of each material were tested. The porosity of each cement was investigated by using micro-computed X-ray tomography. Finite element analysis (FEA) was used to simulate three retrograde conical cavity preparations with an apical diameter of 1 mm (Tip I), 1.4 mm (Tip II), and 1.8 mm (Tip III) after an apical 3 mm resection. BR demonstrated the lowest compression strength values (17.6 ± 5.5 MPa) and porosity percentages (0.57 ± 0.14%) compared to BD (80 ± 17 MPa-1.22 ± 0.31%) and WR (90 ± 22 MPa-1.93 ± 0.12%) (p < 0.05). FEA demonstrated that the larger cavity preparation demonstrated higher stress distribution in the root whereas stiffer cement demonstrated lower stress in the root but higher stress in the material. We can conclude that a respected root end preparation associated with cement with good stiffness could offer optimal endodontic microsurgery. Further studies are needed to define the adapted cavity diameter and cement stiffness in order to have optimal mechanical resistance with less stress distribution in the root.

Artificial Intelligence as a Decision-Making Tool in Forensic Dentistry: A Pilot Study with I3M.

Expert determination of the third molar maturity index (I3M) constitutes one of the most common approaches for dental age estimation. This work aimed to investigate the technical feasibility of creating a decision-making tool based on I3M to support expert decision-making. Methods: The dataset consisted of 456 images from France and Uganda. Two deep learning approaches (Mask R-CNN, U-Net) were compared on mandibular radiographs, leading to a two-part instance segmentation (apical and coronal). Then, two topological data analysis approaches were compared on the inferred mask: one with a deep learning component (TDA-DL), one without (TDA). Regarding mask inference, U-Net had a better accuracy (mean intersection over union metric (mIoU)), 91.2% compared to 83.8% for Mask R-CNN. The combination of U-Net with TDA or TDA-DL to compute the I3M score revealed satisfying results in comparison with a dental forensic expert. The mean ± SD absolute error was 0.04 ± 0.03 for TDA, and 0.06 ± 0.04 for TDA-DL. The Pearson correlation coefficient of the I3M scores between the expert and a U-Net model was 0.93 when combined with TDA and 0.89 with TDA-DL. This pilot study illustrates the potential feasibility to automate an I3M solution combining a deep learning and a topological approach, with 95% accuracy in comparison with an expert.

The Medical, Clinical, and Radiographic Aspects of Multiple Idiopathic Tooth Resorption: A Systematic Review.

BACKGROUND: Many causes of resorption remain unclear and are thus identified as idiopathic. In such cases, management is difficult, especially when multiple teeth are involved. The aim of the present study was to assess the literature regarding the medical, clinical, and radiographic aspects of multiple idiopathic resorptions (MIR) and to examine the factors associated with the risk of extraction. METHODS: The title and protocol were registered a priori in PROSPERO (CRD42020191564), and the study followed the PRISMA methodology. Four electronic databases were searched to include reviews and case reports on MIR in permanent dentition. RESULTS: Among the 1035 articles identified, 31 case reports were included. The mean age of the patients was 32 years (SD = 16.4). MIR were consistently diagnosed after radiographic evaluation and were undetected during intra-oral examination in 62% of cases. The treatment involved extraction in 77% of cases. The risk of extraction increased in the presence of periodontal inflammation. CONCLUSIONS: MIR are aggressive forms of resorption requiring routine visits. MIR mostly involve extraction and lead to a challenging prosthetic rehabilitation due to severely damaged abutment teeth. However, the current knowledge on MIR remains fragmental and based on a limited number of case reports.

Precision medicine using patient-specific modelling: state of the art and perspectives in dental practice.

The dental practice has largely evolved in the last 50 years following a better understanding of the biomechanical behaviour of teeth and its supporting structures, as well as developments in the fields of imaging and biomaterials. However, many patients still encounter treatment failures; this is related to the complex nature of evaluating the biomechanical aspects of each clinical situation due to the numerous patient-specific parameters, such as occlusion and root anatomy. In parallel, the advent of cone beam computed tomography enabled researchers in the field of odontology as well as clinicians to gather and model patient data with sufficient accuracy using image processing and finite element technologies. These developments gave rise to a new precision medicine concept that proposes to individually assess anatomical and biomechanical characteristics and adapt treatment options accordingly. While this approach is already applied in maxillofacial surgery, its implementation in dentistry is still restricted. However, recent advancements in artificial intelligence make it possible to automate several parts of the laborious modelling task, bringing such user-assisted decision-support tools closer to both clinicians and researchers. Therefore, the present narrative review aimed to present and discuss the current literature investigating patient-specific modelling in dentistry, its state-of-the-art applications, and research perspectives.

Multifactorial Analysis of Endodontic Microsurgery Using Finite Element Models.

BACKGROUND: The present study aimed to classify the relative contributions of four biomechanical factors-the root-end filling material, the apical preparation, the root resection length, and the bone height-on the root stresses of the resected premolar. METHODS: A design of experiments approach based on a defined subset of factor combinations was conducted to calculate the influence of each factor and their interactions. Sixteen finite element models were created and analyzed using the von Mises stress criterion. The robustness of the design of experiments was evaluated with nine supplementary models. RESULTS: The current study showed that the factors preparation and bone height had a high influence on root stresses. However, it also revealed that nearly half of the biomechanical impact was missed without considering interactions between factors, particularly between resection and preparation. CONCLUSIONS: Design of experiments appears to be a valuable strategy to classify the contributions of biomechanical factors related to endodontics. Imagining all possible interactions and their clinical impact is difficult and can require relying on one's own experience. This study proposed a statistical method to quantify the mechanical risk when planning apicoectomy. A perspective could be to integrate the equation defined herein in future software to support decision-making.

A critical analysis of research methods and experimental models to study pulpitis.

Pulpitis is the inflammatory response of the dental pulp to a tooth insult, whether it is microbial, chemical, or physical in origin. It is traditionally referred to as reversible or irreversible, a classification for therapeutic purposes that determines the capability of the pulp to heal. Recently, new knowledge about dental pulp physiopathology led to orientate therapeutics towards more frequent preservation of pulp vitality. However, full adoption of these vital pulp therapies by dental practitioners will be achieved only following better understanding of cell and tissue mechanisms involved in pulpitis. The current narrative review aimed to discuss the contribution of the most significant experimental models developed to study pulpitis. Traditionally, in vitro two (2D)- or three (3D)-dimensional cell cultures or in vivo animal models were used to analyse the pulp response to pulpitis inducers at cell, tissue or organ level. In vitro, 2D cell cultures were mainly used to decipher the specific roles of key actors of pulp inflammation such as bacterial by-products, pro-inflammatory cytokines, odontoblasts or pulp stem cells. However, these simple models did not reproduce the 3D organisation of the pulp tissue and, with rare exceptions, did not consider interactions between resident cell types. In vitro, tissue/organ-based models were developed to better reflect the complexity of the pulp structure. Their major disadvantage is that they did not allow the analysis of blood supply and innervation participation. On the contrary, in vivo models have allowed researchers to identify key immune, vascular and nervous actors of pulpitis and to understand their function and interplay in the inflamed pulp. However, inflammation was mainly induced by iatrogenic dentine drilling associated with simple pulp exposure to the oral environment or stimulation by individual bacterial by-products for short periods. Clearly, these models did not reflect the long and progressive development of dental caries. Lastly, the substantial diversity of the existing models makes experimental data extrapolation to the clinical situation complicated. Therefore, improvement in the design and standardisation of future models, for example by using novel molecular biomarkers, databased models and artificial intelligence, will be an essential step in building an incremental knowledge of pulpitis in the future.

Analytical model of I-bar clasps for removable partial dentures.

OBJECTIVE: Clasps of removable partial dentures (RPDs) often suffer from fatigue stress that leads to plastic deformation, loss of retention, and RPD failure. Recently, computer-based technologies were proposed to optimize clasp geometry design. The objective of this study was to create an analytic model of I-bar clasps for computer-aided design (CAD)-RPD. METHODS: The analytical model based on mechanical laws was established to simulate I-bar clasp retention, and optimize its design. The model considered the lengths of the vertical (L1) and horizontal (L2) arms of the I-bar as well as the radius (r) of its half-round cross-section. The analytical model was validated with mechanical experiments evaluating the retention of cobalt-chromium (Co-Cr) clasps in vitro and compared with finite element analysis (FEA). RESULTS: The analytical model was in good agreement with the mechanical experiments and FEA, and showed that I-bar clasp design could provide optimal mechanical performance as long as the length of arms (L1 and L2) do not exceed 6 mm. Clasps with L1 > 8 mm and L2 > 9 mm presented stress values exceeding the fatigue limit of Co-Cr. The proposed solution was to increase the radius of I-bar to conserve the initial mechanical performance of Co-Cr. SIGNIFICANCE: Co-Cr I-bar clasps perform best on teeth with reduced mesiodistal dimensions (canine and premolar), and their designs could be optimized to prevent stress from reaching the yield strength and the fatigue failure limit.

Assessing decision-making in education of restorative and prosthetic dentistry: a pilot study.

PURPOSE: To evaluate whether a concordance assessment (CA) software application is able to assess decision-making in restorative and prosthetic dentistry. MATERIALS AND METHODS: Vignettes representing 10 different clinical situations were integrated into a software application. Each vignette included 3D digital models and a short case, as well as 5 therapeutic options rated on a 4-point Likert scale (-2 = strongly contraindicated; -1 = contraindicated; +1 = indicated; +2 = strongly indicated). A panel of 15 dental educators (9 educators from the prosthetic department [PD] and 6 from the conservative department [CD]) had to evaluate the indication of each of the 5 therapies for the 10 vignettes. RESULTS: This pilot questionnaire showed good internal consistency on most therapies (Cronbach's α = 0.86), with the exception of more recently introduced therapies (overlay/veneerlay and endocrown). On a maximum score out of 100, the average of CD educators (79.2 ± 3.2) was not significantly different (P = .73) from that of a PD educator (77.8 ± 3.5). Scores ranged from 66.8 to 89.6. Analysis of the expert panel's responses also reported mostly (34/50) a distribution of responses that was characteristic of CA and uncertain situations. CONCLUSION: The present software application was able to reproduce and assess decision-making in dentistry with satisfying internal consistency of educators.

Immersive 3D Educational Contents: A Technical Note for Dental Educators.

Three-dimensional files featuring patients' geometry can be obtained through common tools in dental practice, such as an intraoral scanner (IOS) or Cone Beam Computed Tomography (CBCT). The use of 3D files in medical education is promoted, but only few methodologies were reported due to the lack of ease to use and accessible protocols for educators. The aim of this work was to present innovative and accessible methodologies to create 3D files in dental education. The first step requires the definition of the educational outcomes and the situations of interest. The second step relies on the use of IOS and CBCT to digitize the content. The last "post-treatment" steps involve free software for analysis of quality, re-meshing and simplifying the file in accordance with the desired educational activity. Several examples of educational activities using 3D files are illustrated in dental education and discussed. Three-dimensional files open up many accessible applications for a dental educator, but further investigations are required to develop collaborative tools and prevent educational inequalities between establishments.